#include<stdio.h>
#include<stdlib.h>
#define len(array) sizeof(array)/sizeof(*array)
void swap(int* a, int* b);

int main(){
    int a, b;
    a = 1;
    b = 2;
    printf("%d, %d\n", b, a);
    swap(&a, &b);
    printf("%d, %d\n", a, b);
    return 0;
}

void swap(int* a, int* b){
    printf("%d, %d\n", a, b);
    int* temp = a;
    a = b;
    b = temp;
    printf("%d, %d\n", a, b);
}